Questions

The International Day for Biological Diversity (IDB) is observed every year on May 22 to increase understanding and awareness of biodiversity issues. The 2017 theme “Biodiversity and Sustainable Tourism” provides an opportunity to raise awareness and action towards the important contribution of sustainable tourism both to economic growth and to the conservation and sustainable use of biodiversity.

Looking at the diagram in  rows, the central circle equals half the sum of the numbers in the other circles to the left and right of the centre.

Those are stairs which goes up and down without moving.

Rolling friction or rolling drag is the force resisting the motion when a body rolls on a surface. It is mainly caused by non-elastic effects, that is, not all the energy needed for deformation of the wheel, roadbed, etc... is recovered when the pressure is removed.

Another cause of rolling resistance lies in the slippage between the wheel and the surface, which dissipates energy.

Abhinav Bindra is an Indian professional shooter who is the world and Olympic champion in the 10 m air rifle event.